KR100722530B1 - Method for manufacturing the high strength ultra-fine/nano-structured aluminum composite materials strengthened with quasi-crystalline phases by mechanical milling/alloying - Google Patents

Abstract

The present invention is characterized by providing a method of manufacturing a high-strength semi-crystalline reinforced aluminum composite material after mechanical milling / alloying the mixed powder of the semi-crystalline powder and the aluminum powder or alloying elements, followed by a hot forming process.

The present invention is an ultrafine / nanostructured aluminum composite material having superior strength at room temperature and high temperature than a composite material prepared by simply mixing a mixed powder of a semicrystalline phase powder with an aluminum powder or an alloying element by using a mechanical milling / alloying process. It provides a method for producing a.

Mechanical milling / alloying, ultra fine / nanostructures, aluminum composites, semi-crystalline phases, hot forming

Description

Method for manufacturing the high strength ultra-fine / nano-structured aluminum composite materials strengthened with quasi-crystalline phases by mechanical milling / alloying}

1 is a process flowchart showing a manufacturing process of the present invention;

2 is an X-ray diffraction pattern diagram of an Al ₆₅ Cu ₂₀ Fe ₁₅ semicrystalline phase immediately after the die casting method and after heat treatment at 860 ° C. for 3 hours.

3 is a transmission electron microscope limited field diffraction diagram of the Al ₆₅ Cu ₂₀ Fe ₁₅ quasi-crystalline phase prepared by the die casting method,

FIG. 4 shows the volume ratios of (a) 10%, (b) 20%, and (c) 30 of the Al ₆₅ Cu ₂₀ Fe ₁₅ semicrystalline phase powder and the aluminum powder after mechanical milling / alloying, followed by hot extrusion. Optical micrograph of composite material

5 is an aluminum / quasicrystalline composite material having a volume ratio of 20% of the semicrystalline phase prepared by hot extrusion after mechanical milling / alloying Al ₆₅ Cu ₂₀ Fe ₁₅ semicrystalline powder and aluminum powder, using a transmission electron microscope. (a) a bright field image, (b) a dark field image,

6 is a graph showing the results of compression testing at room temperature of a composite material prepared by hot extrusion after mechanical milling / alloying Al ₆₅ Cu ₂₀ Fe ₁₅ semicrystalline powder and aluminum powder;

7 is a graph showing the results of a compression test at 200 ° C. of a composite material prepared by hot extrusion after mechanical milling / alloying Al ₆₅ Cu ₂₀ Fe ₁₅ semicrystalline powder and aluminum powder,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an aluminum / quasicrystalline or aluminum alloy / quasicrystalline composite material in which microcrystalline particles are finely and uniformly dispersed using a mechanical milling / alloying process. Particularly, the present invention relates to a semicrystalline powder and an aluminum powder or an alloy element. The present invention relates to a method for producing an ultrafine / nano structure high strength aluminum / quasicrystalline phase or aluminum alloy / quasicrystalline phase composite material through mechanical milling / alloying a mixed powder with a hot forming process.

In general, the quasi-crystalline phase has five, eight, ten, or twelve rotationally symmetric axes that do not appear in the crystal, and has a structure between the crystalline phase and the amorphous state. Quasi-crystalline phases have been found in many alloys since they were found in Al-Mn alloys, and are currently found in Al-Cu-Fe, Al-Pd-Mn, Al-Cu-Cr, Al-Cu-Ru, Al-Li-Cu It is reported that relatively stable quasicrystalline phases are formed in alloys such as Al-Ni-Co and Al-Cu-Co. The quasi-crystalline phase exhibits unique physical properties such as low thermal and electrical conductivity, high hardness, and low coefficient of friction due to its unique atomic arrangement. In addition, since the semi-crystalline phase has a very high hardness, but almost no ductility, the semi-crystalline phase alone is difficult to commercialize as a structural material. However, since the high hardness of the quasi-crystalline phase can be used as a discontinuous reinforcement of the composite material, recently, a quasi-crystalline phase-reinforced composite material using such a quasi-crystalline phase has been developed.

As a method for producing a semicrystalline phase-reinforced composite material, the base metal powder and the semicrystalline phase powder are uniformly mixed, followed by cold forming, and then a hot pressurization process, a hot water purification pressurization process, and a hot extrusion process are used. However, in the case of hot mixing of the base metal powder and the semi-crystalline powder, followed by hot forming, and the process of adding the semi-crystalline powder to the aluminum molten metal, the non-uniform distribution of the semi-crystalline reinforcement material and the There are problems such as fragile interface formation and rapid coarsening of the base metal grains during hot forming.

The present invention was devised to solve the above problems of the prior art, and an object of the present invention is mechanical milling instead of conventional processes such as simple mixing method and melt casting method in the preparation of semi-crystalline reinforced aluminum matrix or aluminum alloy matrix composite material. Using a alloying process to provide a method for producing composite materials in which the microcrystalline reinforcement is refined and uniformly distributed, the stable interface between the semicrystalline reinforcement and the aluminum base is formed, and the strength of the aluminum matrix does not occur during the hot forming process. There is.

In order to achieve the above object, the present invention is characterized by producing a composite material in which semicrystalline phase particles are uniformly and finely dispersed by mechanical milling / alloying a mixed powder of semicrystalline phase powder with aluminum powder or an alloying element. It provides a method for producing a high strength semi-crystalline phase-reinforced ultra-fine / nano structure aluminum composite material by mechanical milling / alloying.

The present invention is to prepare a semi-crystalline phase by a process such as gas spraying, mold casting, arc melting, etc., mechanically milling / alloying the semicrystalline powder together with aluminum powder or mixed powder with alloying elements to produce aluminum / quasicrystalline phase or aluminum It provides a manufacturing method comprising the step of preparing an alloy / quasi-crystalline composite powder, forming the composite powder into a healthy composite material through a cold forming process, a degassing process and a hot forming process.

In addition, the present invention provides a method for producing an aluminum / semicrystalline phase or aluminum alloy / semicrystalline phase composite material, characterized in that the volume ratio of the semicrystalline phase is 5 to 50%. When the quasi-crystalline phase is added at a volume ratio of 5% or less, the reinforcing effect by the reinforcement phase is insignificant, and when it is added at a volume ratio of 50% or more, it is difficult to manufacture a sound molded product without defects by the hot forming process, so it is outside this range. It is undesirable to add a semicrystalline phase.

The present invention also provides a method for producing an aluminum / quasicrystalline phase or aluminum alloy / quasicrystalline phase composite material, wherein the quasi-crystalline phase uses a relatively stable phase even during the hot forming process of the aluminum composite material.

In addition, the present invention is an aluminum / semi-crystalline or aluminum alloy / semi-crystalline composite material having an ultra-fine or nanostructure of the grain size and reinforcement phase of aluminum or aluminum alloy matrix by the mechanical milling / alloying process of 10㎛ or less It provides a method of manufacturing.

In addition, the present invention is added to at least one element of solid solution strengthening elements Mg, Ag, Mn to the aluminum base at a weight ratio of 0.1% to less than the solid-solution limit, or the precipitation strengthening elements Cu, Zn, Si, Ti, Fe, Li, Sn At least one element of Cr, Zr or more is added to the solid solution or at least 0.1 to 10.0 of the rare earth elements Y, Ce, La, Sc, Sm, Nd, Gd, and Pr or a misch metal Mechanical milling, comprising adding 0.1% to 50% by weight of one or more alloying elements of W, Mo, Co or one or more of Al ₂ O ₃ , SiC, AlN, Si ₃ N ₄ Provides a method for producing a high strength semi-crystalline phase reinforced ultrafine / nano structured aluminum composite material by alloying.

EMBODIMENT OF THE INVENTION Hereinafter, with reference to drawings, the structure of this invention is demonstrated in detail.

1 is a process flowchart showing a method of manufacturing an aluminum / quasicrystalline phase or an aluminum alloy / quasicrystalline phase composite material according to the present invention.

In general, the preparation of the quasi-crystalline phase can be produced by gas spraying, mold casting, arc melting, etc., and may include a subsequent heat treatment process to generate a quasi-crystalline phase. 2 is an X-ray diffraction pattern of (a) and (b) after heat treatment at 860 ° C. after preparing a quasi-crystalline phase having an Al ₆₅ Cu ₂₀ Fe ₁₅ composition. Immediately after casting, diffraction patterns of β-phase (AlFe (Cu)), λ-phase (Al ₁₃ Fe ₄ ), and Al ₆₅ Cu ₂₀ Fe ₁₅ quasi-crystalline phases were observed, but after heat treatment, the Al ₆₅ Cu ₂₀ Fe ₁₅ quasi-crystalline phase Only the diffraction pattern of was observed, indicating that the proportion of the quasi-crystalline phase was increased through subsequent heat treatment. Since the quasi-crystalline phases produced by the die casting method and the arc melting method are in a bulk state, they need to be pulverized into powder prior to mechanical milling / alloying. Since the semicrystalline phase is brittle, the semicrystalline phase powder having a desired size can be selected by mechanical grinding and sieving.

Mechanical milling / alloying is performed by loading grinding media such as raw powder, steel balls and ceramic balls together in grinding equipment such as ball mills and attritors, and then Effects of repeated fracture and cold welding of raw material powder during repeated collisions, refinement of the structure, refinement and uniform distribution through pulverization and mixing of the reinforcement phase, and alloying beyond the high solubility limit It is a process to obtain. In order for the mechanical milling / alloying to take place effectively, the ratio of the grinding media to the raw powder is in the ratio of 5: 1 to 50: 1, and an inert gas is used to prevent excessive oxidation of the raw powder and the reinforcing material during the mechanical milling / alloying process. A device is needed to maintain the atmosphere.

In the present invention, it is possible to refine the microcrystalline phase uniformity and the uniform distribution of the semi-crystalline reinforcement material and the grain size of the aluminum or aluminum alloy matrix through mechanical milling / alloying, and the aluminum / semi-crystalline phase or aluminum alloy / semi-preparation prepared through the hot forming process The effect of strengthening the strength of the normal composite material can be obtained.

The hot forming step may be performed by a hot pressing step, a hot isostatic pressing step, a hot extrusion step, or the like.

Hereinafter, the present invention will be described in detail with reference to the following Examples, but the present invention is not limited by the Examples.

(Example 1)

In order to prepare a semicrystalline powder, an alloy having a composition of 65% aluminum, 20% copper, and 15% iron was melted using a high frequency induction furnace, and then cast in a steel mold, to increase the fraction of the semicrystalline phase, at 860 ° C. Heat treatment was performed for 3 hours at. FIG. 2 shows only the diffraction patterns of Al ₆₅ Cu ₂₀ Fe ₁₅ semicrystalline phases after heat treatment with X-ray diffraction patterns after the main structure (a) and after heat treatment (b). Means that.

Figure 3 shows the result of obtaining the limited-field diffraction diagram using the transmission electron microscope for the quasi-crystalline powder prepared above, it can be seen that the quasi-crystalline phase having 10 rotational symmetry axis.

The Al ₆₅ Cu ₂₀ Fe ₁₅ semi-crystalline phase prepared by the above process was selected by powder grinding of less than 150㎛ through mechanical grinding and classification process, and mixed with aluminum powder so that the volume ratio of Al ₆₅ Cu ₂₀ Fe ₁₅ semi-crystalline phase is 10%. Mechanical powder was milled and alloyed to prepare composite powder. In order to produce a healthy molded body of the prepared composite powder, the composite powder was filled into an aluminum can and cold pressed, and then the can was welded with a lid with an aluminum tube. Thereafter, the molded body was manufactured by a hot extrusion process after degassing at 540 ° C. while evacuating the aluminum can with a vacuum (1 × 10 ⁻¹ torr or less is appropriate).

(Example 2)

The molded article was manufactured by mechanical milling / alloying and hot extrusion to mix the aluminum powder so that the volume ratio of the Al ₆₅ Cu ₂₀ Fe ₁₅ semicrystalline phase prepared in the same manner as in Example 1 was 20%.

(Example 3)

The molded article was manufactured by mechanical milling / alloying and hot extrusion to mix the aluminum powder so that the volume ratio of the Al ₆₅ Cu ₂₀ Fe ₁₅ semicrystalline phase prepared in the same manner as in Example 1 was 30%.

(Example 4)

The aluminum-magnesium alloy was prepared so that the content of magnesium, a typical solid solution strengthening element, together with aluminum powder was 4% by weight in total, so that the volume ratio of Al ₆₅ Cu ₂₀ Fe ₁₅ semicrystalline phase prepared in the same manner as in Example 1 was 25%. The powder was mixed with the powder to produce a molded body through mechanical milling / alloying and hot extrusion.

(Example 5)

Al ₆₅ Cu ₂₀ Fe ₁₅ prepared by the same process as in Example 1 was mixed with the copper powder so that the content of copper, a typical precipitation hardening element, and 5% by weight of the total weight ratio of the aluminum powder together with the aluminum powder to 25% Molded bodies were prepared by mechanical milling / alloying and hot extrusion.

(Example 6)

Alumina (Al ₂ O ₃ ), which is a representative ceramic reinforcing material, together with aluminum powder so that the volume ratio of Al ₆₅ Cu ₂₀ Fe ₁₅ quasi-crystalline phase prepared in the same process as Example 1 is 5% by weight in the total The molded body was prepared by mixing with alumina powder through mechanical milling / alloying and hot extrusion.

The microstructure of the aluminum / quasicrystalline composites prepared according to Examples 1 to 3 was observed, and the results are shown in FIG. 4. It can be seen that the Al ₆₅ Cu ₂₀ Fe ₁₅ quasi-crystalline phase is uniformly and finely distributed in the hot extruded composite material. The microstructure of the aluminum / quasicrystalline composite prepared according to Example 2 was observed by transmission electron microscope, and the results are shown in FIG. 5. It can be seen that the aluminum matrix grains of the composite material subjected to hot extrusion have a nanostructure of 200 nm or less. Compression tests were performed at room temperature and high temperature on the aluminum / quasicrystalline composites prepared according to Examples 1 to 3, and the results are shown in Table 1 and FIGS. 6 to 7.

division Example 1 Example 2 Example 3 Compressive yield strength (MPa at R.T.) 477 513 613 Compressive yield strength (MPa at 200 ℃) 259 260 295

The aluminum alloy / quasi-crystalline composites prepared according to Examples 4 to 6 were subjected to compression tests at room temperature, and the results are shown in Table 2.

division Example 4 Example 5 Example 6 Comparative Example 1 Comparative Example 2 Comparative Example 3 Compressive yield strength (MPa at R.T.) 714 701 614 139 171 413

※ Comparative Example 1 is an aluminum / quasi-crystalline composite material obtained by adding Al ₆₂ Cu ₂₆ Fe ₁₂ quasi-crystalline phase prepared by gas spraying to molten aluminum at 750 ° C. so as to have a volume ratio of 10%. Al ₆₂ Cu ₂₆ Fe ₁₂ Aluminium / quasi-crystalline composites with volume ratio of 20% (SM Lee, JH Jung, E. Fleury, WT Kim and DH Kim: Materials Science & Engineering A, 294-296 (2000) ) p.99).

※ Comparative Example 3 is an aluminum alloy / silicon carbide composite material prepared by powder metallurgy by mixing 6061 aluminum powder and silicon carbide (SiC) in a volume ratio of 20% (ASM handbook, vol.21, Composite, p.153 . Reference)

As a result of Table 1, in the case of the composite material in which the Al ₆₅ Cu ₂₀ Fe ₁₅ semicrystalline phase was manufactured by mechanical milling / alloying, pure aluminum matrix was used as in Example 1, and the strength was general even though the volume ratio of the semicrystalline phase was 10%. It turns out that it exceeds the strength of an aluminum alloy. As shown in Examples 2 and 3, when the volume ratio of the quasi-crystalline phase is increased to 20 or 30%, it can be seen that the increase in strength at room temperature and high temperature is remarkable. In addition, using the Al ₆₂ Cu ₂₆ Fe ₁₂ quasi-crystalline phase of a composition similar to that used in the present invention, compared to Comparative Examples 1 and 2 showing the strength of the aluminum / quasi-crystalline composite material produced by the casting method prepared by mechanical milling / alloying The composite material exhibits three times more strength. This is due to the mechanical milling / alloying, the strength is improved by the miniaturization and uniform dispersion of the semi-crystalline reinforcement and the ultra fine / nano structure of the aluminum matrix grains.

As a result of Table 2, when magnesium was added as the solid solution strengthening alloy element of aluminum as in Example 4, and when copper was added as the precipitation strengthening alloy element of aluminum as in Example 5, ceramic strengthening as in Example 6 When alumina was added, 20 to 40% of the strength-improving effect was obtained compared to the case where only the semi-crystalline reinforcing material was added. This is due to the mechanical milling / alloying of the composite material to improve the strength of the composite material by strengthening the aluminum matrix and grain refinement.

According to the present invention, by using the mechanical milling / alloying process as in the present invention in the preparation of the semi-crystalline reinforcement aluminum composite material, it is fine compared to the conventional manufacturing process such as powder metallurgy process or melt casting process, which simply undergoes mixing process of powder. It is possible to manufacture composite materials with uniform distribution of reinforcement phase, improved strength and thermal stability, and it is very effective when applied to industrial fields requiring high specific strength at room temperature and high temperature.

Claims (5)

Preparation of a composite material in which the semi-crystalline particles are uniformly and finely dispersed by a mechanical alloying or a mechanical milling process in which the mixed powder of the heat-treated semicrystalline powder and the aluminum powder or alloy element is maintained in an inert gas atmosphere. A method for producing a high strength semi-crystalline phase-reinforced ultrafine nanostructured aluminum composite material by mechanical alloying or mechanical milling. The method of claim 1, The quasi-crystalline phase has a volume ratio of 5 to 50%, the method of manufacturing a high strength semi-crystalline phase-reinforced ultra-fine nanostructure aluminum composite material by mechanical alloying or mechanical milling, characterized in that. The method according to claim 1 or 2, The quasi-crystalline phase is a high-strength semi-crystalline phase-reinforced ultrafine nanostructure aluminum composite material by mechanical alloying or mechanical milling, characterized in that the Al ₆₅ Cu ₂₀ Fe ₁₅ quasi-crystalline phase which is stable at high temperatures during the hot forming process of the aluminum composite material. Way. The method according to claim 1 or 2, By the mechanical alloying or mechanical milling process, it is characterized in that the aluminum and semi-crystalline or aluminum alloy and semi-crystalline composite material having an ultrafine nanostructure having a grain size and reinforcement phase of aluminum or aluminum alloy matrix of less than 10㎛ Method for producing a high strength semi-crystalline reinforced ultra-fine nanostructure aluminum composite material by mechanical alloying or mechanical milling. The method according to claim 1 or 2, wherein at least one element of Mg, Ag, Mn, which is a solid solution strengthening element, is added to the aluminum matrix at a weight ratio of 0.1% to a solid solution limit, or Cu, Zn, Si, Ti, At least one element of Fe, Li, Sn, Cr, Zr is added above the solubility limit, or at least one element of rare earth elements Y, Ce, La, Sc, Sm, Nd, Gd, Pr or misch metal Add 0.1 to 10.0% by weight, or add 0.1 to 50% by weight of one or more elements of W, Mo, Co alloy elements or ceramic particles of Al ₂ O ₃ , SiC, AlN, Si ₃ N ₄ Method for producing a high strength semi-crystalline phase-reinforced ultrafine nanostructure aluminum composite material by mechanical alloying or mechanical milling, characterized in that.

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